Conformable and thick belts have been increasingly used in recent years in printer and photocopying machines, because they provide numerous benefits over thin, hard belts. In particular, the use of conformable and thicker belts allows throughput to be increased, permits greater media latitude, and provides flexibility in terms of the fusing process, release, and image quality. For example, a conformable and thick belt can be used in a printer or photocopy machine with two rigid rollers where the belt forms the nip, may or may not carry the image, and is the only consumable.
Initially, flexible belts were fabricated by taking two ends of a web material and fastening them together by a variety of techniques such as sewing, wiring, stapling, providing adhesive joints, etc. While such joined or seamed belts are suitable for many applications, such as the delivery of rotary motion from a source such as a motor, to implement a device such as a saw blade, they are not as satisfactory in many of the more sophisticated applications of belt technology in common practice today.
In the technology of the current day, many applications of belts require much more sophisticated qualities and utilities. For example, in electrostatographic imaging processes which use a flexible photoreceptor belt or a flexible electroreceptor belt, in combination with either a intermediate transfer member, or image transport devices, or a fusing member, or transfix devices in the flexible belt form, more sophisticated belts are necessary.
It is ideal to provide a seamless conformable belt whereby there is no seam in the belt which mechanically interferes with any operation that the belt performs or any operation that may be performed on the belt. While this is ideal, the manufacture of seamless belts requires rather sophisticated manufacturing processes which are expensive. Typically, seamless belt fabrication is approximately 5–10 times more expensive than seamed belt fabrication. Larger belts are also very difficult to handle in the seamless belt fabrication process. As a result, various attempts have been made to provide seamed belts which can be used in these processes. Previous attempts to manufacture seamed belts have largely relied on belts where the two opposite ends of a rectangularly cut sheet of the belt material have been lapped or overlapped and ultrasonically welded to form the seam.
The belts formed according to the lapping or overlapping and ultrasonic welding technique have excessive seam thickness which provides a bump or other discontinuity in the belt surface. This leads to a significant height differential over the adjacent portions of the belt, of at least 0.003 inches or more depending on the belt thickness, which leads to performance failure in many applications.
In an electrostatographic imaging process utilizing an overlapping ultrasonically welded seamed belt, two severe problems that are encountered during the imaging and cleaning processes are cleaning the imaging belt of residual toner after transfer of the toner image due to the excess in seam height and dynamic fatigue seam cracking as a result of large induced bending stress caused by the increase in seam thickness. In particular, with a bump, crack, or other discontinuity in the seam area of the belt, the cleaning function of a blade is affected which allows toner to pass under the blade and not be effectively cleaned off from the imaging belt surface. A crack in the seam may also become a site that collects and traps toners which are eventually spewed out to the imaging zones of the imaging belt surface causing copy printout defects.
Furthermore, seams having differential heights may, when subjected to repeated striking by cleaning blades, cause the untransferred, residual toner to be trapped in the irregular surface morphology of the seam. As a consequence, an electrostatographic imaging belt which is repeatedly subjected to this striking action, during imaging and cleaning processes, tends to delaminate at the seam. Since the severe mechanical interaction between the cleaning blade and the seam also causes blade wear problems, the result often observed is that both the cleaning life of the blade and the overall life of the imaging belt under a service environment can be greatly diminished as well as degrading the copy print-out quality.
In addition, the mechanical striking of the cleaning blade over the excessive seam height has also been found to give rise to vibrational disturbance in the imaging development zone which affects the toner image formation on the belt and degrades resolution and transfer of the toner image to a receiving copy sheet. Moreover, the discontinuity or seam bump in such a belt may result in inaccurate image registration during development, inaccurate belt tracking, and overall deterioration of motion quality, as a result of the translating vibrations.
It has been shown that an endless seamed belt, having very small seam height differential, can be formed with patterned interlocked ends, the pattern of the ends being formed by using a laser or a die to cut the pattern and the patterned cut ends being brought together to interlock to form a seam. However, such interlocking seams require careful control of the properties of the adhesive used to bond together the seam ends and careful control of the thickness of the bonded seam.